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Saturday, September 15, 2007

More on plate discipline

Earlier this season, Pizza Cutter published an interesting study (which I summarized here) that attempted to more carefully assess batter patience and discipline. Pizza's study looked at player at-bats and categorized each swing or non-swing into categories: correct decisions (swinging and making contact, taking a ball), incorrect decisions (swinging and missing, hitting a ball foul with less than two strikes, or taking a strike). His findings indicated, among other things, that Adam Dunn made a lot of mistakes, most specifically that he seemed to take too many pitches. He also found that someone like Scott Hatteberg tended to make very few mistakes overall.

The primary limitation of Pizza Cutter's study was that he was unable to assess where the pitches actually were in the strike zone. Players like Vladimir Guerrero had very high "correct decision" rates, even though scouting data indicates that he swings at a lot of bad balls...and makes contact. The result was some uncertainty about what these values really tell us about a player. For example, despite Adam Dunn's high "incorrect decision" rate, he is still a prolifically productive offensive ballplayer, and his extreme patience does result in a lot of walks, which is a big part of his offensive game. So perhaps his approach is still a good one?

Yesterday, Dan Fox published a study (subscription req'd) that in many ways fills in some of the gaps in Pizza Cutter's methodology using the PITCHf/x data from MLB Gameday. With these data, he can identify strikes and balls independent of hitters' decisions on how to respond to them. He can then assess hitters' success rates in responding to different sorts of pitches. He has yet to release a spreadsheet containing all of these data--I'm hopeful he will at some point, but those BPro folks tend to like to keep things under wraps--but here's what I was able to pull out about particular Reds hitters from his article.

Legend (approx mean values in parentheses):Square (0.87) - % of pitches in strike zone that a hitter swung at and made contact with.Fish (0.325) - % of pitches outside of strike zone that hitter swung at.BadBall (0.73) - % of pitches out of strike zone that a hitter swung at and made contact with.Eye (0.25) - % of pitches in strike zone taken for strikes (excludes 3-0 counts).* Data values in italics were among the most extreme in Fox's dataset. Blue values are "better" than average, red values are "worse" than average.* Order is as they appear in Fox's article. After the first six, I'm eyeballing the numbers from Fox's graphs.

Name

Pitches

Square

Fish

BadBall

Eye

Keppinger, J

426

0.982

0.216

0.860

0.361

Phillips, B

698

0.899

0.446

0.705

0.215

Hatteberg, S

519

0.911

0.229

0.866

0.245

Conine, J

298

0.888

0.229

0.872

0.280

Hamilton, J.

435

0.858

0.349

0.711

0.102

Hopper, N.

---

0.365

0.189

Encarnacion, E.

---

0.375

0.212

Ross, D.

0.305

0.302

Gonzalez, A.

0.392

0.305

Dunn, A.

0.290

0.202

Griffey, K.

0.315

0.256

Fox presented the following categories of hitters, based on his Fish and Eye stats. I've identified Reds that fall into each category:

Disciplined:Doesn't swing at "bad" pitches, swings at "good" pitches in the strike zone.

Scott Hatteberg - completely consistent with Pizza Cutter's data.

Adam Dunn - Needless to say, this is inconsistent with Pizza Cutter's data. His data would put Dunn into the next category. I can't really speculate on the cause, except that Fox's data are all '07 data, while PC's data were for '06, when Dunn clearly had an off year. Maybe we're seeing the change in his approach? I'd love to know what Dunn's Square rating was...because there's got to be some reason that he strikes out so much.

Jeff Keppinger - Keppinger's fish rating was among the lowest in baseball, indicating that he almost never goes after a bad pitch. And his square rating was also among the highest in baseball, indicating that even though he may take too many pitches, if he swings he will nearly always make contact.

Jeff Conine - I probably shouldn't include this ex-Red, but I thought it interesting that he combined excellent ability to hit bad balls with a tendency to avoid swinging at them. In other words, he's intelligently selective with regards to his bad ball hitting.

David Ross - One of the things that really helped Ross's numbers last year, in addition to his fine power, was his ability to take a walk. This indicates that he has continued to try to be patient this season. Unfortunately, his walk rate is down. Perhaps taking all those strikes is part of why he's struggled? Another guy who I'd love to see Square data on.

Ken Griffey - Griffey's almost dead-on average for "eye," so he barely makes this category. In general, he seems to be a well-disciplined hitter.

Aggressive: Swings at bad pitches, but also swings at good pitches in the strike zone.

Brandon Phillips - Surprise, surprise. Phillips is nothing if not an aggressive hitter.

Norris Hopper - Again, surprise, surprise. As a confidence builder, it's good to see my own observations of hitter tendencies reflected in these data.

Josh Hamilton - This one did surprise me. Hamilton always seems to me to be pretty patient, and his walk totals generally support that. But he may be a bit of a victim of the dichotomous way I categorized folks here--in truth he's fairly average for most values...except Eye. Hamilton has the lowest eye score in Fox's dataset, indicating that he will swing at almost anything in the strike zone. Can't fault a guy for being aggressive on balls in the zone. Joe Sheehan's work certainly indicates that this will tend to result in higher BABIP than swinging at balls out of the zone, as does John Walsh's recent study.

Edwin Encarnacion - Eddie showed good on-base ability last season, though in truth his OBP might have been slightly "inflated" by a tendency to get hit by pitches. This year, and especially in August, he has been more aggressive. It shows in these data.

Pitchers' Friends: Swings at too many balls outside of zone, takes too many pitches in the zone.

Alex Gonzalez - Gonzalez has never been much of an on-base threat, instead deriving most of his offense (when there's any present at all) from his power, which is decent for a middle infielder. This might show part of the reason for that -- a tendency to chase bad balls, and a tendency to take a lot of strikes.